a) Field of the Invention
This invention relates to a resorbable fixation device for treating torn bodily material in vivo.
b) Background Art
Internal fixation of facial bones is usually performed using various types of metallic dynamic compression plates, miniplates and adequate screws. Although metallic implants give satisfactory fixation and good fracture healing, it is recommended to remove them after the fracture healing is completed. This is basically due to potential corrosion of the implants, bone resorption under the implant and possible inflammatory response to the implant. The use of resorbable implants with adequate mechanical properties and rate of resorption might allow to overcome these problems.
Traumatic injury and/or heavy load applied to the knee may result in torn menisci. The early methods of treatment of the torn menisci involved partial or total meniscectomy. The long term results of the latter technique proved to be disappointing, and often led to osteoarthritis and instability of the knee. The new techniques of menisci lesions repair involve meniscus suturing using arthrotomy and arthroscopy. An arthrotomy is quite traumatic, as it requires large incision to gain access to the joint. An arthroscopy allowing guiding the suture under arthroscopic visualization is less traumatic, although it also requires incision which is larger than the standard one used in arthroscopy.
From U.S. Pat. No. 4,884,572 BAYS ET AL. a fixation device is known for repairing torn cartilaginous or other bodily tissue, particularly torn meniscus tissue during arthroscopic surgery. This known repair device in the form of a tack has a shaft portion with radially projecting barb members and a longitudinal bore. It is made from a biodegradable material chosen to have a degradation time in excess of the required healing time for the tissue, i.e. glycolide and lactide copolymers. This known device of conventional design seems to improve the torn meniscus treatment technique because it requires only a small incision. It is not possible, however, to use it for treatment of small fragments due to its lack of sufficient stiffness.
It is further known to use resorbable pins (marketed under the trademarks ORTHOSORB, ETHIPIN and BIOFIX) for the fixation of small fragments, treatment of fractures of the ankle, talus, patella, condylar fractures of the femur, fractures of the metacarpals and phalanges of the hand, condylar fractures of the humerus, a.s.o. These known pins have a circular cross-section and a smooth surface. The latter may give rise to pin loosening due to the slippage of the smooth surface through the bone hole. In addition, in their present design and sizes, they are available only with one stiffness.